var arr = ['短跑', '接力', '短跑', '拔河', '跳绳', '接力', '拔河', '跳远']
function unique(arr) {
    var newArr = []
    for (var i = 0; i < arr.length; i++) {
        if (newArr.indexOf(arr[i]) === -1) {
            newArr.push(arr[i])
        }
    }
    return newArr;
}
console.log(unique(arr));